Enforce that stored ranges straddle zero.
Enforce that stored ranges straddle zero.

This is working around a floating point bug that can result in the min value being derived to be a very small positive number (~1e-36) for ranges that naturally include 0 (i.e. RELU).

PiperOrigin-RevId: 221332354

tensorflow/lingvo,tensorflow/lingvo,tensorflow/lingvo,tensorflow/lingvo